A reciprocating internal combustion engine such as that in an automobile is one example of an engine that includes an integral lubrication system. Such a lubrication system supplies lubricant (e.g., oil) for limiting friction and transporting heat away from critical moving components. Loss of oil pressure in the lubrication system can result in damage, if not catastrophic failure, of such machine due to as excessive friction and/or heat retention. For example, in an automobile engine, high lateral g-force such as those encountered in race applications can cause oil in an oil sump (e.g., oil pan) to move away from a pickup tube of an oil pump within the oil sump thereby resulting in a sudden and often dramatic drop in oil pressure within the lubrication system (i.e., a loss of oil pressure). Such a loss in oil pressure, even for fractions of a second, can result in loss of lubrication that causes damage to surface of engine components that are in moving relation to other components. Examples of such components include, but are not limited to, camshafts, crankshafts, pistons, lifters, oil pump impellers, bearings, and the like.
An engine oil accumulator is a reservoir of pressurized engine oil that works to reduce engine oil pressure fluctuations. Such fluctuations can be exhibited as a partial or the complete loss of oil pressure. AccuSump, which is the trademark name of Canton racing Products, is one example of a commercially available engine oil accumulator. When engine oil pressure suddenly drops, such as under high g-force causing the oil in the oil sump to move away from the pickup tube of the oil pump, the engine oil accumulator discharges oil under sufficient pressure to provide continued flow of oil to the engine under suitable pressure. The engine oil accumulator is re-charged by directing a portion of oil flow from the oil pump to the engine oil accumulator during normal operation of the engine lubrication system (i.e., the engine lubrication system having ample capacity to supply pressurized oil to meet the demands of the engine and to deliver oil under pressure into the engine oil accumulator (e.g., an oil reservoir thereof)). Thus, it can be seen that an engine oil accumulator functions as a mechanical oil pressure dampener.
In basic operation of known engine oil accumulators, an accumulator is allowed to discharge oil into a connected lubrication system at any time when the engine is running. A refinement of such basic operation is to allow the engine oil accumulator to discharge oil into the connected lubrication system only when oil pressure within the connected lubrication system is above a certain lower-limit threshold level. Such a refinement prevents the engine oil accumulator from discharging oil when the engine is in an idling condition and/or at a low rpm condition. For example, a commercially available valve offered by Canton racing Products under the tradename ACCUSUMP EPC Valve allows flow into the engine oil accumulator only when engine oil pressure is below a threshold engine oil pressure (i.e., allows it to charge and prevents it from discharging), and allows bi-directional flow when engine oil pressure is above a threshold engine oil pressure thereby allowing the engine oil accumulator to charge and discharge (i.e., via mechanical control means only). Effectively, the ACCUSUMP EPC Valve causes an engine oil accumulator to operate normally (i.e., as a mechanical oil pressure dampener) only above the threshold engine oil pressure, and shuts it off below that threshold, thereby preventing it from discharging when the engine is operating at low engine speeds and engine load.
In the lubrication system of a reciprocating internal combustion engine, engine oil pressure/flow demands are generally not constant. Under high engine speeds and engine loads, greater oil pressure/flow is required to carry frictional heat away from engine components and maintain an oil film of sufficient viscosity for hydrodynamic lubrication of said components. Engine load is a measurement of how hard an engine is working, and can be calculated from a variety of parameters, including but not restricted to, engine speed, throttle position, mass air flow, volumetric air flow, intake air temperature, intake manifold pressure, exhaust manifold pressure, torque and horsepower. An engine requires less oil pressure/flow when operating at low engine speeds and light engine load (such as when idling or cruising at constant highway speeds), but requires more oil pressure/flow when operating at high engine speeds and high engine load (such as when rapidly accelerating the vehicle and/or propelling the vehicle uphill).
A common (and simplified) guideline for engine oil pressure/flow requirement for a typical reciprocating internal combustion engine is that engine oil pressure should increase 10 psi for every 1000 rpm of engine speed. More complex guidelines may be determined, such as derived from a Stribeck curve for a specific engine and engine oil, which may express an engine oil pressure/flow requirement in terms of, but not restricted to, the following parameters—engine speed, oil temperature, and engine load. A variety of methods exist for determining the oil pressure requirement, the choice of which depends on the user.
A skilled person will appreciate that oil pressure or oil flow demands in an engine are not constant across all operating conditions. Therefore, an oil pressure/flow controlling apparatus that causes pressurized oil to be discharged from an accumulator by comparing current engine oil pressure against a specified engine oil pressure threshold overcomes drawbacks associated with conventional engine oil accumulators and methods for facilitating oil delivery therefrom, thus making such an oil pressure/flow controlling apparatus advantageous, desirable and useful.